Xen Opens Up a Little More

The latest version of the Xen hypervisor offers new API support, improved 64-bit paravirtualization and the ability to move virtual machines on the fly.

The Xen open source project released a new version of the Xen hypervisor this week with a little help from Intel, IBM, Novell, VA Linux (Japan), HP, Fujitsu, SGI, Red Hat, AMD, Sun, Unisys and
the National Security Agency.

Xen 3.1 extends the open source virtualization technology with new API support, improved 64-bit paravirtualization and a feature for moving virtual machines (VMs) on the fly. Xen is an included component in a number of Linux distributions, including Red Hat, Novell and Ubuntu.

The open source effort has benefited greatly from community contributions and is considered a viable competitor to industry leader VMware.

"For server workloads, Xen's core hypervisor functionality
now meets or beats VMware ESX in pretty much all areas,
both features and performance," Ian Pratt, leader of the
Xen project and founder of XenSource, told
internetnews.com.

One of the key new features in Xen 3.1 is Live Relocation. Live Relocation
is the ability to move a running virtual machine from one
physical server to another with virtually no interruption
to the operating system and applications running in it
(just a couple of hundred milliseconds during the final
switchover).

"It basically works by synchronizing the memory image of
the running virtual machine between the source and
destination hosts, and then migrating the final CPU state
etc," Pratt said. "VMware calls this feature
'VMotion.'"

While Xen has benefited greatly from the contributions of
its community, with the XenAPI, the hypervisor will become
even more extensible.

"The XenAPI can control pretty much all aspects of Xen," Pratt
said. "You can provision new VMs, perform lifecycle
management operations, and live relocate VMs, etc."

Though Xen 3.1 is now available, it will take a bit more
time until the new hypervisor finds its way into the
XenSource commercial offering.

XenSource
is the commercial backer behind Xen and offers additional
technology and support offerings on top of the open source
base. The latest XenEnterprise
offering from XenSource is actually numbered XenEnterprise 3.2.

"Although there is a substantial user and developer
community that tests Xen open source release candidates, it
does take further soak testing and certification to
'harden' an open source Xen release into the quality
required for XenEnterprise," Pratt explained.

"XenSource has invested
heavily in verification lab automation, so the process
usually takes just two to three months."

Moving beyond the 3.1 release, Pratt has his eye on what he
referred to as a number of interesting new hardware
features arriving soon in CPUs, chipsets and network cards
that are very useful for virtualization. His plan is to
make sure Xen has great support for these features ahead
of them shipping.

"Laptops and desktops are among the most interesting areas
for focus going forward," Pratt said. "We want to make
sure we do a good job of 3-D graphics virtualization, power
management, USB, etc."